This invention relates to inherently water-dispersible compounds which cure upon exposure to heat and to the use of such compounds to produce water-insoluble materials.
Most coating and other product formulations are employed in a fluidized state and are then dried or cured to solid continuous films or articles that are water-resistant. The films are also adherent to the substrate to which they are applied. Thus such fluid formulations usually contain a vehicle and miscellaneous ingredients such as pigments, extenders, fungicides and the like. The vehicle is a fluid consisting of a solution or a mixture of a binder with a thinner or solvent. The binder is the primary constituent since it binds itself and any optional ingredients to the substrate or surface of the object being coated. See, for example, Bobalek and Fisher, Organic Protective Coatings, Reinhold, (1953); and Martens, Emulsion and Water-Soluble Paints and Coatings, Reinhold, (1964). To enable the coatings to dry or cure to form continuous adhesive films, binders that are polymeric or polymerize after application to the substrate have generally been employed. In order that the coatings have a desired water resistance, the binders used are generally hydrophobic and are therefore, not soluble in water. Thus, the liquid thinner or solvent usually required to fluidize the binder, has generally been an organic solvent such as xylene, toluene, various alcohols and the like. Such solvents are generally more expensive than water and are often toxic or flammable, thus requiring expensive precautions when coating formulations containing them are stored and used.
In view of the foregoing disadvantages of such organic solvents or thinners, it is highly desirable to employ a binder which can be dissolved or thinned by water and yet will produce a water-resistant film when applied to a substrate and then dried or cured. While coating formulations having latex binders wherein the hydrophobic binder is colloidally dispersed in an aqueous dispersing medium are used widely in the coating industries, such coatings suffer from various shortcomings. For example, the flow properties are often not as satisfactory as those wherein the binder is dissolved in an organic liquid. Also undesirable coagulation of the latex can occur when the formulation is exposed to low temperatures. Also well-known, the water-borne synthetic resinous binders such as amino-functionalized epoxies and carboxylated acrylates have the disadvantage of significant water sensitivity and require high curing temperatures and cross-linking agents such as amine/aldehyde condensates and blocked polyisocyanates.
In view of these problems with the aforementioned water-dispersible and water-soluble binders, recent attempts have been made to prepare coating formulations containing water-soluble binders which convert to highly water-resistant coatings upon curing. Examples of such product formulations are described in U.S. Pat. Nos. 3,544,499 and 4,020,030. Unfortunately, however, while the sulfonium-containing binders described in the aforementioned references cure to form highly water-resistant materials, they generally evolve an undesirable odorous vapor during the curing process.
In view of the deficiencies of the prior art product formulations, it is now highly desirable to provide a water-soluble binder material which cures to a highly water-resistant material without evolving an odorous vapor.